FIXUP: sched: fix set_cfs_cpu_capacity when WALT is in use

The CPU utilization reported when WALT is in use already tracks the
contributions due to RT and DL workloads. However, SchedFreq exposes
different capacity update functions, one for each class, and does classes
utilization internally at update_cpu_capacity_request() call time.

This patch ensures that when WALT is in use, the:
  cpu_sched_capacity_reqs::cfs
value is tracking just the load generated by SCHED_OTHER tasks.

Change-Id: Ibd9c9a10874a1d91f62477034548f7664e57cd6a
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 51c632bc94b6fe6fd5103c481a7430daa22a95e3..0b1bd6e8e1c8dc5a349b7b9efbf70f91302aa036 100644 (file)
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1611,8 +1611,27 @@ void update_cpu_capacity_request(int cpu, bool request);
 static inline void set_cfs_cpu_capacity(int cpu, bool request,
                                        unsigned long capacity)
 {
-       if (per_cpu(cpu_sched_capacity_reqs, cpu).cfs != capacity) {
-               per_cpu(cpu_sched_capacity_reqs, cpu).cfs = capacity;
+       struct sched_capacity_reqs *scr = &per_cpu(cpu_sched_capacity_reqs, cpu);
+
+#ifdef CONFIG_SCHED_WALT
+       if (!walt_disabled && sysctl_sched_use_walt_cpu_util) {
+               int rtdl = scr->rt + scr->dl;
+               /*
+                * WALT tracks the utilization of a CPU considering the load
+                * generated by all the scheduling classes.
+                * Since the following call to:
+                *    update_cpu_capacity
+                * is already adding the RT and DL utilizations let's remove
+                * these contributions from the WALT signal.
+                */
+               if (capacity > rtdl)
+                       capacity -= rtdl;
+               else
+                       capacity = 0;
+       }
+#endif
+       if (scr->cfs != capacity) {
+               scr->cfs = capacity;
                update_cpu_capacity_request(cpu, request);
        }
 }